The psoas is one of the flexors of the hip.
It flexes the hip joint together with the ilacus muscle. When the thigh is fixed (stable) it flexes the trunk as it sitting up from a supine position.
They both flex the thigh.
psoas major muscle
The psoas nerve is the nerve that innervates the psoas major muscle. It is formed by fibers of spinal nerves L2-L4.
Iliopsoas or Psoas Major
The Iliopsoas
The strongest Flexor of the hip (thigh) is illiopsoas muscle which is the merger of the illiacus and the psoas major muscle. The illiacus is on the medial side of the pelvic bone attaching to the femur and the psoas major muscle attaches from the lumbar vertebrae to the femur.
The tenderloin is made up of the psoas major and psoas minor muscles, which start on the cow's lower spine, run through the pelvis and connect to the front of the femur.
The combination of the Psoas major and the Illiacusmuscles is called the Illiopsoas and is the muscle you seek.
Yes, like any muscle it can be strained.
The Psoas uscle
composed of two muscles Iliacus and psoas major Iliacus: prime mover for flexing thigh or for flexing trunk on thigh on thigh during a bow. Psoas major: same as iliacus, also effects latera flexion of vertebral column; important postural muscle.
The psoas muscle starts the the letters "ps."
erector spinae? I believe it is the iliopsoas (combination of the psoas major, psoas minor, and iliacus.) On a sidenote it also flexes the thigh.